Heat 1 tbsp oil in a wide pan and fry the pancetta for 2 mins on each side. Drain on kitchen paper, then crumble. Fry the onion in the same pan for 5 mins until soft.

Stir in the rice and garlic for 2 mins to coat in the oil. Add half the stock, bring to the boil and simmer for 5 mins until absorbed. Add the remaining stock, a ladleful at a time, constantly stirring until the rice is tender, about 20 mins.

Stir in most of the watercress and the parmesan. Season well. Add the lemon zest and a squeeze of juice.

Spoon half the risotto onto a plate (use for lunch the next day, see tip below). Add the prawns to the pan and cook for 2 mins until pink. Toss the rest of the watercress with 1 tsp oil and lemon juice. Serve over the risotto with some pancetta and parmesan.